Cowher, on the other hand, believes the injury occurred when Roethlisberger hit his thumb on either his own arm or a jersey. "It's hard to see on film," Cowher said.
Roethlisberger felt better Thursday morning and Cowher said if he continues to improve he'll play in Saturday's preseason game against the Minnesota Vikings at Heinz Field. Cowher also said no further tests are necessary and that he doesn't believe the injury is related to the hairline fracture on the same thumb that plagued Roethlisberger last season. Roethlisberger said there could be a relationship between the injuries.
"Same thumb," he said, "so it might have something to do with it."
"He's been fine," Cowher said. "There's been no problem with it the whole camp. He's been throwing the ball good."
Charlie Batch would replace Roethlisberger Saturday and would play a quarter -- "give or take a series or two" – with the rest of the starters.
"We'll get him just enough work to keep him sharp and no more," Cowher said.
"They'll both play," Cowher said of his first-year quarterbacks. "I don't want to say one's three and one's four. They're both going to play and we'll go from there."
The remainder of the Pittsburgh Steelers' injury report includes four players who are out: center Chukky Okobi (neck), tight end Jerame Tuman (hamstring), and wide receivers Hines Ward (hamstring) and Isaac West (knee). Three players are questionable: Roethlisberger, wide receiver Sean Morey (thumb) and linebacker Clint Kriewaldt (groin).
On Ward, Cowher said: "He's as frustrated as anybody. He's trying everything and anything. It's eating at him not to be out there. He likes to practice. You almost have to get him to be patient with this. Yeah, I'd like to see him out there; I'd like to see everybody out there. But you have to be smart with this and recognize the length of the season. We know about Hines. That's not something I'm concerned with. But a hamstring is not something you screw around with. We're going to err on the side of caution with him."
Duce Staley was given Wednesday off and on Saturday Cowher promised to give him time behind the first-team line. It reads like an audition for a 31-year-old player who's been slow and plodding in practice, but Cowher said otherwise.
"He's looked good," Cowher said. "We gave him the day off. He has a little wear and tear on his body and sometimes you have to do that with players his age and at this point in his career. Like I said, he just needs to play to get back into the running shape and get the feel for the running game. And we've got to give him a chance to run behind a good offensive line just to get a sense for where he is."
As bad as Staley has looked this camp, his roster spot might be secure due to a lack of depth, although Cowher had kind words for seventh-round pick Cedric Humes.
"Cedric's doing fine. I think he's getting more comfortable," Cowher said. "He made a couple of plays last week. Again, he'll get some chances to work in the second halves of these games and it's going to be very important for him as a runner, but also in the kicking game. Those are the things that will play very heavily into those decisions these next three games."
FREE SAFETY DERBY
Ryan Clark will start at free safety Saturday instead of Tyrone Carter, as Cowher promised last week when he named Carter the starter for the first game. Cowher said he's in no rush to name the full-time starter.
"I have not put a timetable on it," he said. "Troy [Polamalu] has worked with both of those guys and they've all kind of worked together. We've inter-mixed them enough with Ty and Ryan. Both of those guys have worked with the first group. I don't think there will be any kind of acclimation that will need to take place when we make a decision because they both have been in there enough that we'll be fine at that position."
With the prognosis for injured backup center Chukky Okobi yet to be determined, Cowher will continue looking at Kendall Simmons at center.
"We'd like to at least get him some preseason work either this week or next week," Cowher said of his starting right guard.
As for Okobi, Cowher said: "He's still got to get all of his feeling back and his strength back in his arm. I think we'll have a better sense for that on Monday. Again, he could be ready for the last preseason game, but we aren't going to mess around with that. We will err on the side of caution with the neck."
Okobi showed up at practice in uniform and snapped for seven-on-seven passing drills.